Diesel exhaust after treatment involves the use of a selective catalyst reducer (SCR) and a diesel particulate filter (DPF) along with injection of urea-water solution and diesel fuel into the exhaust gas. The performance, durability and cost of these devices depend strongly on the evaporation and mixing of the injected fluid into the exhaust gas. The injected fluid can be a liquid, gas or a mix of both phases. Therefore, mixers are placed in the exhaust flow to maximize evaporation (if a liquid is being injected) and mixing of the injected fluid (both liquid and vapor phases) with the exhaust gas. However, certain mixers and mixing configurations, in use presently, are insufficient in the vaporization and mixing of the injected fluid, are complex in design and therefore difficult to manufacture and package, costly and/or generate unacceptable backpressure within the exhaust flow, e.g., the backpressure is the additional pressure drop in the exhaust system due to the introduction of the mixing device(s) and its negative consequences for engine performance such as power and fuel economy.
In view of the foregoing, an improved fluid mixer and evaporator having a relatively simple design, is easy to manufacture, has high durability and/or is low in cost while still maintaining relatively low or acceptable back pressure within the exhaust system is desired.